This invention relates generally to color electrophotographic reproduction apparatus, and more particularly to an improved color electrophotographic reproduction apparatus having two photoconductive members on which different latent image charge patterns corresponding to related color images are respectively formed simultaneously, and wherein a substantial portion of the transfer of marking particle developed images of such patterns to a receiver member occurs simultaneously.
In making multicolor reproductions with an electrophotographic reproduction apparatus for example, a multicolor original document is illuminated and color separation images are formed. The color separation images expose respective image-receiving areas of a uniformly charged photoconductive member to form spaced latent image charge patterns on the member respectively corresponding to the color separation images. The latent image charge patterns are respectively developed with complementary primary colored marking particles (toner) to form developed images. The developed images are then transferred from the photoconductive member to a receiver sheet in superimposed relation to form a multicolor reproduction (copy) of the document. An illustrative example of such an apparatus is shown in U.S. Pat. No. 3,841,751 issued Oct. 15, 1974 in the name of Draugelis et al.
Since the multicolor reproduction is madeup of a plurality of marking particle developed images of latent image charge patterns on a photoconductive member proceeding serially through electrophotographic process stations, the time for making the multicolor reproduction is significantly longer than that for producing a monochrome reproduction where the process stations function at an equivalent speed. Furthermore, tracking of the photoconductive member (both cross-track and in-track) must be precisely controlled if the three or more image-receiving areas bearing the developed images are to arrive at the transfer station at the same relative location so that the developed images can be transferred to the receiver sheet in accurate superimposed register. The need for cross-track control of the photoconductive member between image-receiving areas can be eliminated by providing a plurality of spaced photoconductive members bearing the plurality of developed images respectively (see for example, U.S. Pat. No. 4,162,843 issued July 31, 1979 in the name of Inoue et al). However, with plural photoconductive members complexities arise in accurately projecting color separation images onto the plurality of photoconductive members, and sequentially registering a receiver sheet with the respective members bearing the developed images for accurate superimposed transfer. Further, the reproduction rate remains reduced because the respective transfers to a receiver sheet take place sequentially at spaced locations.